What are the requirements to apply for a single entry type O immigration visa based on marriage to a Thai woman, and how does leaving Thailand affect my visa status?

To apply for a single entry type O immigration visa at a Thai embassy abroad based on marriage to a Thai citizen, you typically need to provide documentation such as proof of marriage (marriage certificate), a passport, visa application forms, and possibly financial statements to show sufficiency of funds. After obtaining the visa, if you leave Thailand during the one-year period, your visa remains valid; however, it's essential to ensure you do not overstay. Generally, a re-entry permit can be purchased to maintain your visa status when exiting and entering Thailand.